userland: start refactor to show failing values on failure!

aarch64 basically done, but missing:

- other archs
- maybe convert main.c into C++ to use templates?
- full review of ASSERT_EQ calling convention issues not seen by tests
  by chance
- documentation

userland/arch/main.c

@@ -9,11 +9,53 @@
 
 int asm_main(uint32_t *line);
 
+#define ASSERT_EQ_DEFINE(bits) \
+    int assert_eq_ ## bits(uint ## bits ## _t val1, uint ## bits ## _t val2) { \
+        if (val1 != val2) { \
+            printf("%s failed\n", __func__); \
+            printf("val1 0x%" PRIX ## bits "\n", val1); \
+            printf("val2 0x%" PRIX ## bits "\n", val2); \
+            return 1; \
+        } \
+        return 0; \
+    }
+
+ASSERT_EQ_DEFINE(32)
+ASSERT_EQ_DEFINE(64)
+
+int assert_memcmp(const void *s1, const void *s2, size_t n) {
+    int ret;
+    size_t i;
+    uint8_t *s1b, *s2b;
+    uint8_t b1, b2;
+
+    ret = 0;
+    s1b = (uint8_t *)s1;
+    s2b = (uint8_t *)s2;
+    for (i = 0; i < n; ++i) {
+        b1 = s1b[i];
+        b2 = s2b[i];
+        if (b1 != b2) {
+            printf(
+                "%s failed: "
+                "byte1, byte2, index: "
+                "0x%02" PRIX8 " 0x%02" PRIX8 " 0x%zx\n",
+                __func__,
+                b1,
+                b2,
+                i
+            );
+            ret = 1;
+        }
+    }
+    return ret;
+}
+
 int main(void) {
     uint32_t ret, line;
     ret = asm_main(&line);
     if (ret) {
-        printf("error %d at line %d\n", ret, line);
+        printf("error: asm_main returned %d at line %d\n", ret, line);
     }
     return ret;
 }